Capital punishment has been a feature of the Arizona criminal justice system since 1865, when Dolores Moore became the first recorded execution in the federal territory that is now the state of Arizona. 108 executions were carried out in Arizona before the national moratorium on executions was imposed by the US Supreme Court in 1972. Executions were generally carried out by method of hanging until 1934, when the first execution by gas chamber was carried out in Arizona. Lethal injection became Arizona's primary method of execution on November 15th of 1992, however those sentenced to death before that date may still elect lethal gas as their method of execution.

Famous Cases

Tison v. Arizona: Perhaps the most infamous death penalty cases in the history of Arizona had their inception in a 1978 prison break. Gary Tison and his cellmate Randy Greenawalt, both serving life sentences for previous murders, escaped from Arizona State Prison with the help of Tison's three sons and lackadaisical prison visitation rules. After disabling the prison's phone and alarm system the gang fled toward the California border. After the getaway vehicle used by the group blew a tire, Gary Tison killed the family that stopped to offer assistance, taking their vehicle and fleeing towards Colorado. The group killed another couple for their vehicle in Colorado, fleeing back into Arizona. After running one roadblock set up by police, they ran into a second roadblock that was better prepared. A shootout resulted, killing one of Tison's sons. The rest tried to escape on foot, and although Greenawalt and two of Tison's sons were caught quickly, Gary Tison escaped into the desert. His body was discovered 11 days later. The remaining Tisons and Greenawalt were charged with 92 crimes, including several counts of capital murder, even though they had not been the ones to pull the trigger. In 1986 this issue came before the Supreme Court of the United States, with the Tison brothers arguing that Arizona's felony murder statute was unconstitutional because it allowed for the death penalty for those other than the actual killer. In a 5-4 decision, the Supreme Court rejected their appeal, stating that major participants in a felony who exhibit extreme indifference to human life are eligible for the death penalty. Although Greenawalt was executed in 1997, the Tison brothers had their sentences reduced.

Ring v. Arizona: In this 2002 ruling, the Supreme Court of the United States held that jurors, rather than a judge, must be allowed to determine whether a defendant is eligible for a death sentence. The finding of the Court rested on their previous ruling in Apprendi v. New Jersey: if a particular element of the crime or sentencing factor exposed a defendant to harsher punishment, a jury must find that factor. The Supreme Court found no logical or compelling reason to exempt capital cases from this requirement. After the Supreme Court's ruling, the Arizona legislature met in an emergency session to mend the death penalty statute to meet the guidelines laid down by the Supreme Court, providing that jurors, not judges, would be responsible for imposing a death sentence.

Notable Exonerations

On April 8, 2002, Ray Krone was released from Arizona prison after DNA evidence exonerated him. He had been convicted and sentenced to death in 1992, based on circumstantial evidence and testimony stating that bite marks on the victim's body matched Krone's teeth. His conviction was overturned, but he was retried and sentenced to life in prison. DNA evidence was not presented in Krone's original trial, and tests for his second trial were inconclusive. In 2001, his defense attorney secured a court order to retest the DNA using the latest technology. Those tests found that the DNA did not belong to Krone, but instead came from another man, Kenneth Phillips, who was also in prison in Arizona.

On March 14, 2003, the Pima County Attorney's Office dismissed all charges against death row inmate Lemuel Prion, who had been convicted of murdering Diana Vicari in 1999. In August 2002, the Arizona Supreme Court had unanimously overturned his conviction, stating that the trial court committed reversible error by excluding evidence of another suspect. According to the Supreme Court, "There was no physical evidence identifying Prion as her killer," and the trial court abused its discretion in not allowing the defense to submit evidence that a third party, John Mazure, was the actual killer. Mazure, who was also a suspect in the murder, was known to have a violent temper, saw Vicari the night of her disappearance, concealed information from the police when they questioned him, and "appeared at work the next morning after Vicari's disappearance so disheveled and disoriented that he was fired." The Arizona Supreme Court held that the third-party evidence "supports the notion that Mazure had the opportunity and motive to commit this crime." (Arizona v. Prion, No. CR-99-0378-AP (2002)) Prion's conviction was based largely on the testimony of Troy Olson, who identified Prion as the man who was with Vicari on the night of her murder. However, when police first showed Olson photographs of Prion, Olson could not identify Prion. Seventeen months later, after seeing a newspaper picture of Prion labeling him as the prime suspect in the Vicari murder, Olson believed he could identify Prion. Prosecutors admitted that Prion would most likely have been acquitted if prosecuted under the standards set by the August 2002 ruling. Prion remained incarcerated in Utah for an unrelated crime.